Protocol for the isolation and single-nuclei multiomic analyses of the human fetal epicardium.

The characterization of cell populations that reside in the outer layer of the heart has been hindered by difficulties in their isolation. Here, we present a protocol for isolation and single-nuclei multiomic analyses of the human fetal epicardium. We describe steps for microdissection, isolation, and enrichment of epicardial cells by mechanical dissociations and direct lysis.

Single-nuclei multiomic analyses identify human cardiac lymphatic endothelial cells associated with coronary arteries in the epicardium.

Cardiac lymphatic vessels play important roles in fluid homeostasis, inflammation, disease, and regeneration of the heart. The developing cardiac lymphatics in human fetal hearts are closely associated with coronary arteries, similar to those in zebrafish hearts. We identify a population of cardiac lymphatic endothelial cells (LECs) that reside in the epicardium.

Coronary arterial development is regulated by a Dll4-Jag1-EphrinB2 signaling cascade.

Coronaries are essential for myocardial growth and heart function. Notch is crucial for mouse embryonic angiogenesis, but its role in coronary development remains uncertain. We show Jag1, Dll4 and activated Notch1 receptor expression in sinus venosus (SV) endocardium.